The purpose of our work is to develop and test a new kind of imaging system we call 'palpation imaging'. We expect that palpation imaging will be a useful tool for improving the discrimination between benign and malignant breast tumors. The scope of the effort in our first two years of funding was to implement our algorithm for imaging tissue elasticity on a commercial ultrasound imaging system and to begin testing that new imaging system. These images are produced at substantially real-time frames rates with normal ultrasound B-mode and strain images displayed side-by-side. These algorithms are fully integrated into the commercial system and require no system modifications. Year two efforts also involved increasing the clinical testing of these tools and investigating other elasticity imaging techniques. Breast exams performed on volunteers have shown that palpation imaging techniques are almost identical to the standard clinical breast ultrasound exam. Elasticity image information appears useful for differentiating atypical cysts, fibroadenomas, and invasive ductal carcinomas. Further testing is required to evaluate statistical performance.